Vehicle transmissions typically include multiple gear sets and clutches. Elements of the gear sets are selectively connected to each other and/or a stationary member of the transmission via engagement of one or more of the clutches. A fluid pump and numerous control fluid valves provide hydraulic pressure to the clutches. The fluid pump in some vehicles, such as certain hybrid electric vehicles, may be powered via electricity rather than by an internal combustion engine so as to maintain sufficient hydraulic pressure when the engine is not running. Charging of a hydraulic system refers to the process of filling the fluid passages supplying hydraulic pressure to the various clutches until a desired calibrated line pressure is attained.